#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main() {
    int n, m;
    scanf("%d %d", &n, &m);
    int val[n][m], sum = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            scanf("%d ", &val[i][j]);
            if (val[i][j] > 0) sum += val[i][j];
        }
    }
    printf("%d", sum);
    return 0;
}
